A business relationship has to be just that. Nothing personal.
You can be polite, cordial but not friendly.
Depends on what “but” means, but basically correct. Not “personal”.
Definition of FRIENDLY (webster)
1: of, relating to, or befitting a friend: as a : showing kindly interest and goodwill b : not hostile ; also : involving or coming from actions of one’s own forces <friendly fire> c : cheerful, comforting <the friendly glow of the fire>
2: serving a beneficial or helpful purpose
I see no issue in “showing kindly interest and goodwill” with co-workers whom with you work. One should certainly be “cheerful”, and perhaps even “comforting” at appropriate times.